Question

I have a regular app with a bunch of view controllers – let’s say viewControllerA, viewControllerB, and viewControllerWeb.

“viewControllerWeb” is a UIWebViewDelegate and just has a UIWebView in it. I would like to call methods on it even when I am interacting with viewControllerA or viewCOntrollerB. (methods like [webview stringByEvaluatingJavaScriptFromString:])

So essentially, it seems like I want “viewControllerWeb” to be open in the background somehow. Anyone know how to accomplish something like this? Am I thinking about this the wrong way?

Hope you guys can help me out! Thanks a lot!

Answer 1

Well, if you want to call these methods from the VC where the WebViewController was created, you could easily do that by making webViewController a global variable.

If you want to access it from an outside VC, then you could make WebViewController a singleton that you can access from anywhere inside your app. Something like this would do:

static WebViewController *sharedController = nil;

+ (WebViewController*)sharedController {

    if(sharedController == nil)
        sharedController = [[WebViewController alloc] initWithNibName:@"WebViewController" bundle:[NSBundle mainBundle]];

    return sharedController;
}

That would allow you to access your WebViewController from anywhere:

[[WebViewController sharedController] stringByEvaluatingJavaScript...]

EDIT: As RyanR pointed out in the comment, this obviously will keep your view controller retained until you explicitely release it. Common mistake with singletons is to forget about them and never release them — make sure you do!